Use the macro 'swap()' defined in 'include/linux/minmax.h' to avoid
opencoding it.
Reported-by: NZeal Robot <zealci@zte.com.cn>
Signed-off-by: NYang Guang <yang.guang5@zte.com.cn>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>